Surgery requires the use of surgical instruments within a restricted and unusually sensitive operating field. During surgery, the field becomes crowded if a large number of surgical instruments must be used simultaneously, with concomitant difficulty for the surgical team to maintain a clear viewing area. Under such circumstances, surgical instruments designed to perform more than one task are of particular usefulness.
One technique used extensively in surgery is the placement of sutures, or stitches, to close a wound or incision. Such sutures are usually applied by attaching surgical thread to a curved needle and manipulating the needle through the tissue at the edges of the wound or incision and thereafter drawing the surgical thread tightly to bring the edges of the wound or incision together to facilitate the healing process. Thereafter, the surgical thread is knotted and severed, leaving behind only that much surgical thread required to firmly close the wound.
Because the thread and the needle are necessarily of an extremely small size, it is common for surgeons to use a needle holder, that is, a surgical instrument having an easily gripped and manipulable handle and a pair of cross-action, or scissors-like jaws within which the surgical needle is firmly clamped. The instrument is then manipulated to pierce the tissue with the needle, draw the needle through the tissue and position it for another stroke. After the stitching procedure has been completed, the needle is removed and the thread is knotted, often times by drawing the thread over the needle holder itself to form the knot.
Heretofore, it has been common for a surgeon to use a separate cutting instrument to sever the suture after knotting has been completed. This often times calls for the use of a second person to perform the severing operation or, at the very least, requires the surgeon acting alone to be ambidexterous or unusually well-coordinated to draw the suture taut with the needle holder and sever the suture with a separate cutting instrument. At the very least, the surgeon may be required to put down the needle holder, pick up a cutting instrument to sever the suture, and pick up the needle holder again to begin the next stitch.
Attempts have been made in the past to combine suture-severing and other functions on a single surgical instrument. Exemplary of such prior efforts is U.S. Pat. No. 2,315,326 (Gmeiner), which teaches a surgical instrument having a serrated jaw within which a suturing needle is clamped, a stop block against which the needle abuts, and a cutting edge formed on the jaws behind the stop block. After suturing is completed, the jaws are unlocked to release the needle and the thread is thereafter drawn past the stop block into that portion of the jaws upon which the cutting edge is formed. The suture is then severed.
In U.S. Pat. No. 4,271,838 (Lasner. et al.), a suture cutter is disclosed having a pair of clamping jaws for the needle, a stop block having a cutting edge formed thereon, and a jaw portion over which the stop block is passed to sever a stuture positioned between the jaw portion and the stop block cutting edge.
Another problem to be faced when using a cross-action surgical instrument for the severing of a suture is the tendency of the suture to snag in the joint formed by the hinging together of the instrument's opposed jaws. U.S. Pat. No. 2,726,657 (Tabrah) discloses a snag preventer on a surgical instrument wherein the exposed edges which may effectively snag the suture are beveled or rounded in order to minimize the possibility of such snags. U.S. Pat. No. 3,577,991 (Wilkinson) teaches a forceps having an external covering shield positioned proximate the jaws to prevent snags.
It should be noted that the snagging may occur during the severing operation or during the knotting operation wherein a loop of the suture is commonly drawn over the jaws of the suturing instruments.
Other examples of combined surgical instruments and cutting surfaces also exist. U.S. Pat. No. 4,478,221 (Heiss) teaches and describes a clamp having a slidable cutter which is withdrawn into the instrument when not in use. U.S. Pat. No. Re. 22,857 (Ogburn) teaches a suturing instrument with a pair of jaws used for holding a suturing needle and a suture cutter positioned along the lowermost leg of the suturing instrument.
U.S. Pat. No. 3,443,313 (Profy) teaches a hemostat having separate clamping tips and cutting tips formed proximate each other, with an externally positioned blade along one side of the cutting tip for severing a suture. The clamping tip is then used to remove the suture.
U.S. Pat. No. 1,579,379 (Marbel) demonstrates the use of a surgical instrument having a forward jaw portion used for clamping and a rearward jaw portion used for severing with no stop member therebetween to act as a stop for the suture or as a clamping site for the needle.
U.S. Pat. No. 1,876,792 (Thompson) teaches a clamp having a pair of cutting jaws mounted on the clamping surface. The clamping and cutting jaws are used separately.
U.S. Pat. No. 3,763,860 (Clarke) teaches a laparoscopic instrument having a forward clamping jaw behind which a cutting edge is positioned.
In U.S. Pat. No. 3,840,817 (Violante), a suturing instrument is disclosed which uses a sharpened edge formed on the needle protector to act as a site for severing the suture. A similar teaching is found in U.S. Pat. No. 4,224,947 (Fukuda) wherein an aperture in the needle, through which the suturing thread is drawn, has a sharpened edge against which the suture may be pulled and severed.
U.S. Pat. No. 4,452,246 (Bader, et al.) and corresponding EPO patent No. WO83/00994 teach a surgical instrument having three jaws, one of which has a cutting edge formed thereon and which may be separately moved against a suture held between the remaining two jaws in order to sever the suture.
U.S. Pat. No. 4,375,218 (DiGeronimo) teaches a forceps having mounted thereon a retractable scalpel used for converting the tool from a forceps to a scalpel and vice versa.
There is a need for surgical instruments, such as forceps or needle-holders having suture-severing capabilities manufactured in a compact, uncomplicated device without extra handles, extra cutting elements, extra blades and the like. There is also a need for such instruments to minimize the snagging of the sutures on the instrument. There is a further need to have such an instrument manufactured in a size useful for delicate surgical procedures.
A particular form of surgery requiring extremely delicately carried-out surgical procedures is ophthalmic surgery. Ophthalmic surgery, with its relatively small operating field, and its delicate and vulnerable tissue structures, demands a great deal of dexterity and control on the part of a surgeon. Under such conditions, the use of multiple-function instruments increases the surgeon's effectiveness by requiring fewer instruments to carry out and complete such procedures as suturing.